4909/AFB

DOT SPECIFICATION 21PF-1A AND 21PF-1B OVERPACKS. DOT SPECIFICATION 21PF-1B OVERPACK MANUFACTURED BY NUCLEAR CONTAINERS, INC. OF ELIZABETHTON, TENNESSEE PRIOR TO 11/30/91 ARE NOT AUTHORIZED BY THIS CERTIFICATE. THE PACKAGINGS AUTHORIZED BY THIS CERTIFICATE CONSIST OF OVERPACKS AND VALVE PROTECTION DEVICES (VPD) FOR 76-CM (30-INCH) DIAMETER CYLINDERS CONTAINING ENRICHED URANIUM HEXAFLUORIDE. THE OVERPACK IS A RIGHT CIRCULAR CYLINDER CONSTRUCTED OF TWO STEEL SHELLS. THE VOLUME BETWEEN THE SHELLS IS FILLED WITH WOOD BLOCKS AND FIRE RESISTANT PHENOLIC FOAM. THE VPD CONSISTS OF 3 ALUMINUM INSERTS, 1 SPACER, AND 1 SPIDER. MAXIMUM GROSS WEIGHT OF THE PACKAGE IS 4000 KG (8800 LB). THE REVISION 18 SUPERSEDES ALL PREVIOUS REVISIONS ON 10/01/2007.